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United States Patent |
5,085,882
|
Rausing
|
February 4, 1992
|
Method for the cooling of a product flow containing solid and/or
semisolid foodstuff particles
Abstract
A method for the cooling of a heated, e.g. heat-sterilized, flow containing
particles of foodstuff character is disclosed. The flow is separated into
a high particle flow, and a low particle flow which is cooled separately
from the high particle flow and is used later as a cooling medium for the
cooling of the high particle flow. The method can be used in aseptic
packaging wherein a heat-treated, cooled foodstuff product, e.g. fruit
soup, vegetable soup, meat broth, etc., is packed in sterilized packing
containers, or in packing containers manufactured from sterilized packing
material, under aseptic packing conditions.
Inventors:
|
Rausing; Hans (Wadhurst, GB2)
|
Assignee:
|
Tetra Pak Holdings S.A. (Pully, CH)
|
Appl. No.:
|
606615 |
Filed:
|
October 31, 1990 |
Foreign Application Priority Data
Current U.S. Class: |
426/524; 62/63; 99/470; 165/65; 426/521 |
Intern'l Class: |
A23L 003/00 |
Field of Search: |
426/524,521,523,589,509
99/470
62/63
165/65
|
References Cited
U.S. Patent Documents
4214013 | Jul., 1980 | Hirahara | 426/509.
|
4543263 | Sep., 1985 | Goldhahn | 426/524.
|
4929463 | May., 1990 | Meyer | 426/521.
|
Foreign Patent Documents |
0034291 | Aug., 1981 | EP.
| |
2412316 | Jul., 1979 | FR.
| |
2139994 | Nov., 1984 | GB.
| |
2176688 | Jan., 1987 | GB.
| |
2189586 | Oct., 1987 | GB.
| |
Primary Examiner: Yeung; George
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis
Claims
What is claimed is:
1. A method for the cooling of a heated product flow containing solid
and/or semisolid particles of foodstuff character, comprising the steps
of:
separating the flow at a separation point into a high particle flow having
particles greater than a predetermined size and a low particle flow having
particles smaller than said predetermined size;
cooling said low particle flow; and
subsequently mixing said low particle flow with said high particle flow
downstream of said separation point whereby said cooled low particle flow
serves as a cooling medium for said high particle flow.
2. A method in accordance with claim 1, wherein said product flow is
separated by a pump which continuously separates said low particle flow
and said high particle flow and, after cooling of said low particle flow,
pumps said cooled low particle flow back to mix it again with said high
particle flow.
3. A method in accordance with claim 1, wherein said low particle flow is
smaller by volume than said high particle flow.
4. A method in accordance with claim 1, wherein particles in said product
flow are selected from the group consisting of meat, fruit and vegetables.
5. A method in accordance with claim 4, further including a step of
heat-treating said product flow by ohmic heating.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cooling method and more particularly to
a method for the cooling of a heated flow containing solid and/or
semisolid product particles of foodstuff character.
2. Description of the Related Art
In packing technology, aseptic packaging is frequently used for the packing
of particularly bacteria-sensitive and storage-sensitive products, e.g.
foodstuffs, which can be rapidly destroyed or seriously impaired if they
are subjected to uncontrolled microbiological influences. Aseptic
packaging in principle is based on the concept that the product which is
to be packed should first be sterilized and subsequently be packed in
separately sterilized packing containers, or in packing containers
manufactured from sterilized packing material, under sterile or aseptic
conditions so as to prevent a reinfection of the sterilized product. The
aseptic packing technique has the number of advantages over other
conventional, non-aseptic packing technique from a point of view of
keeping property of the product as well as of distribution. This means,
inter alia, that the aseptically packaged product, whilst preserving
virtually unchanged freshness qualities can be stored during appreciably
longer storage periods than is the case for a corresponding,
non-aseptically packed product. Moreover, such storage of the aseptic
product during the whole of its handling, from the actual packaging to the
final consumer, can take place without any need for cold storage or an
unbroken cooling chain, which appreciably facilitates the distribution of
the product.
Since bacteriia and other microorganisms generally are very
temperature-sensitive and rarely survive at temperatures above approx.
100.degree.-110.degree. C., it is customary for product sterilization on
aseptic packages to be carried out by means of a controlled heat
treatment. This means that the product, according to a predetermined
time/temperature scheme, is heated to, and is maintained at, a temperature
which is high enough for the desired killing or sterilizing effect,
whereafter the product is cooled and is then packed. With the help of
modern aseptic packing machines of the type which form, fill and close
finished packages it is possible at present to carry out the whole aseptic
packing procedure, including product sterilization, continuously on a
large scale.
A heat treatment of the type which has been described above is both simple
and effective from a point of view of sterilization, and in general
functions well with foodstuffs of the type of milk, juice or other liquid
or pumpable, homogeneous products. Treatment may, however become more
problematic and difficult to carry out with more heterogeneously composed
foodstuffs which contain both solid and liquid components. Examples of
products of the last-mentioned heterogeneous type are, for example, meat
broths, vegetable soups and similar mixtures of sauces/juices and
meat/fruit pulp particles. Foodstuffs, whether they are in solid or in
liquid form, are heat-sensitive and may easily be damaged by a heat
treatment if the same is too extensive and/or is performed at too high a
temperature. In order to avoid such a damaging heat effect it is
important, therefore, for the sterilizing heat treatment to be carried out
at a predetermined temperature which is, right for the particular
foodstuff. On the one hand, the temperature should be sufficiently high so
as to ensure a sterilizing effect, but on the other hand the temperature
should not be high enough for the foodstuff to suffer damage or even risk
suffering damage by the treatment. The extent of the heat treatment,
moreover, should be adapted to keep the total heat load on the foodstuff
within such limits that the smallest possible negative effect on the
qualities of the product is assured. This means in practice that the
actual heating process to the desired sterilization temperature preferably
should be as rapid as possible, and that the cooling process after the
sterilization ought to be carried out rapidly also so that the total heat
load on the foodstuff can be kept to a minimum without the sterilization
effect being neglected.
With the help of so-called ohmic heating, which is based on converting
electric energy into thermal energy directly in the foodstuff by allowing
an electrically conducting flow of the product to pass between oppositely
charged electric voltage poles, it is now possible to achieve a very rapid
heating and accordingly a limited heat load on the product inasfar as the
heating part of the sterilizing process is concerned. However, it has
proved to be more difficult to cool the heated product flow equally
quickly, or at least sufficiently quickly, in order to effect minimization
of the total heat load on the product during cooling too. The problem in
particular involves highly viscous, heterogeneous product types containing
both liquid and solid or semisolid components of the afore-mentioned type,
and to a large extent is connected with, or is due to, the fact that as a
rule it is much easier to cool the liquid element in the product than the
solid or semisolid components. The solid or semisolid components require
longer cooling periods, and thereby limit the possibility of carrying out
the cooling process within the desired minimum amount of time. The
drawn-out cooling process and the increased heat load connected therewith
often has led to the solid and/or semisolid components of the finished
product having been subjected to an impairment of quality which expresses
itself, among other things, in a partially lost nutritional content,
impaired chewing resistance, and also generally negatively affected
organoleptic properties. At the same time, the relatively long cooling
transport distances which the product is by necessity forced to travel by
pumps, contributes further to an impairment of the qualities of the
product due to the pumps mechanical effect on the product.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to indicate a new
method of cooling a heated or heat-treated flow containing solid and/or
semisolid particles of foodstuff character without the associated
inconveniences of the type discussed above.
It is another object of the invention to indicate a method for the cooling
of heterogeneously composed, highly viscous products which is both rapid
and effective and which can be integrated very well in a continuous,
aseptic packaging process using modern, rational packing machines.
The above objects as well as other objects not specifically enumerated are
accomplished by a method of cooling in accordance with the present
invention. The method of the present invention for the cooling of a heated
product flow containing solid and/or semisolid particles of foodstuff
character includes the steps of separating the flow into a high particle
flow and a low particle flow, cooling the low particle flow, and
subsequently cooling the high particle flow using the low particle flow as
a cooling medium.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiment of the present invention will be described in
greater detail with reference to the accompanying drawing, wherein like
members bear like reference numerals and wherein:
FIG. 1 is a schematic view of a system for heat sterilizing and then
cooling a product flow.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows schematically a system for heat sterilization and subsequent
cooling of a foodstuff flow containing both liquid and solid or semisolid
phases, e.g. a vegetable soup or a meat/sauce mixture. The system
comprises a heating or heat-sterilizing device 1 with an inlet pipe 2, and
an outlet pipe 3 which in turn is connected to a shunt or parallel duct 4
at branch points 5 and 6 located at upstream and downstream points
respectively. In the duct circuit 4 is arranged a heat exchanger and
cooling device 7 and a pump 8 located before the downstream branch point
6. The outlet pipe 3 may be connected after the downstream branch point 6,
for example, to the product filling pipe of an aseptic packing machine,
not shown, of the type which forms, fills and closes aseptic packages
under aseptic conditions. The heating device 1 may be a conventional heat
exchanger device of the plate type, but is preferably an ohmic heating
device which very rapidly heats the product intended for sterilization to
a predetermined, suitable sterilization temperature. The heat exchanger or
cooling device 7 too may be of the plate type or of some other known kind.
By means of the system shown, the method in accordance with the invention
is carried out in the following manner. The product, for example vegetable
soup or sauce/meat mixture, is conducted through the inlet pipe 2 into the
heating device 1 and is heated to a predetermined sterilization
temperature. The heated or sterilized product is discharged through the
outlet pipe 3 and is divided into a high particle flow and a low particle
flow. The low particle flow is discharged from the pipe 3 through the duct
4 with the help of any suitable separating device which readily lets
through the liquid product phase but which on the other hand prevents
particles above a certain minimum particle size from passing through the
separating unit into the duct 4. The low particle flow is pumped with the
help of the pump 8 through the heat exchanger and cooling device 7 for
cooling by means of heat exchange with a colder medium in a manner known
in itself. From the device 7, the cooled, low-particle flow is pumped back
into the outlet pipe 3 at the branch point 6 where the cooled flow is
remixed with the high-particle flow separated at the branch point 5. At
the remixing point 6 a spontaneous intimate contact occurs between the
cooled flow and the particles in the warmer flow which thereby are
effectively cooled and partly continue to be cooled during the further
progress of the combined flow through the pipe 3 into the packing machine,
not shown in the drawing.
With the help of the method in accordance with the invention, it is thus
possible to cool very rapidly the heated or heat-treated product flow
containing solid and/or semisolid foodstuff particles, and, in particular,
the method has been found to be especially effective in the cooling of
highly viscous product mixtures containing particle fractions larger by
volume than the liquid phase. An effective and rapid cooling is achieved
even if the volume of the liquid component of the product mixture amounts
to not more than a few percent (%) of the solid or semisolid phase.
While this invention has been illustrated and described in accordance with
a preferred embodiment, it is recognized that variations and changes may
be made therein without departing from the invention as set forth in the
claims.
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